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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 99, No. 1, 2004, pp. 73-79
Bioline Code: oc04013
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 99, No. 1, 2004, pp. 73-79

 en In Vivo Binding of the Cry11Bb Toxin of Bacillus thuringiensis subsp. medellin check for this species in other resources to the Midgut of Mosquito Larvae (Diptera: Culicidae)
Lina María Ruiz; César Segura; Judith Trujillo & Sergio Orduz

Abstract

Bacillus thuringiensis subsp. medellin check for this species in other resources produces numerous proteins among which 94 kDa known as Cry11Bb, has mosquitocidal activity. The mode of action of the Cry11 proteins has been described as similar to those of the Cry1 toxins, nevertheless, the mechanism of action is still not clear. In this study we investigated the in vivo binding of the Cry11Bb toxin to the midgut of the insect species Anopheles albimanus check for this species in other resources , Aedes aegypti check for this species in other resources , and Culex quinquefasciatus check for this species in other resources by immunohistochemical analysis. Spodoptera frugiperda check for this species in other resources was included as negative control.

The Cry11Bb protein was detected on the apical microvilli of the midgut epithelial cells, mostly on the posterior midgut and gastric caeca of the three mosquito species. Additionally, the toxin was detected in the Malpighian tubules of An. albimanus, Ae. aegypti, Cx. quinquefasciatus, and in the basal membrane of the epithelial cells of Ae. aegypti midgut. No toxin accumulation was observed in the peritrophic membrane of any of the mosquito species studied. These results confirm that the primary site of action of the Cry11 toxins is the apical membrane of the midgut epithelial cells of mosquito larvae.

Keywords
Diptera - immunohistochemistry - in vivo binding - Bacillus thuringiensis - Cry11Bb toxin

 
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